Mobile VoIP
Mobile VoIP is an extension of mobility to a VoIP Voice over IPnetwork.
There are several methodologies by which a mobile handset can be integrated into a VoIP network. One implementation turns the mobile device into a standard SIP client, which then uses a data network to send and receive SIP messaging, and to send and receive RTP for the voice path. This methodology of turning a mobile handset into a standard SIP client requires that the mobile handset support, at minimum, high speed IP communications. In this application, standard VoIP protocols (typically SIP) are used over any broadband IP-capable wireless network connection such as EVDO rev A (which is synchronously high speed — both high speed up and down), HSDPA, WiFi or WiMAX.
Another implementation of mobile integration uses a softswitch like gateway to bridge SIP and RTP into the mobile network's SS7 infrastructure. In this implementation, the mobile handset continues to operate as it always has (as a GSM or CDMA based device), but now it can be controlled by a SIP application server which can now provide advanced SIP based services to it. Several vendors offer this kind of capability today, including i2Telecom, Tango Networks, Outsmart, NewStep, BridgePort and BroadSoft.
Mobile VoIP will require a compromise between economy and mobility. For example, Voice over Wi-Fi offers potentially free service but is only available within the coverage area of a Wi-Fi Access Point. High speed services from mobile operators using EVDO rev A or HSDPA may have better audio quality and capabilities for metropolitan-wide coverage including fast handoffs among mobile base stations, yet it will cost more than the typical Wi-Fi-based VoIP service.
Mobile VoIP will become an important service in the coming years as device manufacturers exploit more powerful processors and less costly memory to meet user needs for ever-more 'power in their pocket'. Smartphones in mid-2006 are capable of sending and receiving email, browsing the web (albeit at low rates) and in some cases allowing a user to watch TV.
The challenge for the mobile operator industry is to deliver the benefits and innovations of IP without losing control of the network service. Users like the Internet to be free and high speed without extra charges for visiting specific sites. Such a service challenges the most valuable service in the telecommunications industry — voice — and threatens to change the nature of the global communications industry.
Technologies
Mobile VoIP relies on two main technologies:
- UMA — the Unlicensed Mobile Access Generic Access Network, designed to allow VoIP to run over the GSM cellular backbone
- SIP — the standard used by most VoIP services, and now being implemented on mobile handsets
Recent developments
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The mobile VoIP industry is estimated to grow to US$12 billion by 2010 in Europe alone. Four technologies are required for mobile VoIP functionality: a device, client software, a wireless network and a VoIP service.
Throughout the early 2000s, Hewlett-Packard, Symbol Technologies and others have been innovators in Wi-Fi-based handheld devices, as Personal digital assistant or handheld computers for warehousing and other applications. As successive generations of these devices gained in processing power and battery life, their potential use as a platform for mobile VoIP became practical. Using Microsoft Windows CE operating systems, in the summer of 2005 companies delivered practical client software to run on these class of Wi-Fi only, Windows-based PDAs.
In the summer of 2006, a SIP (Session Initiation Protocol) stack was introduced and a VoIP client in the E-series dual-mode Wi-Fi handsets (Nokia E60, Nokia E61, Nokia E70).
From a Wi-Fi network perspective there are several innovations, embedded in the most current vendor Wi-Fi networking equipment for the enterprise and municipal service provider, that makes them particularly powerful in a mobile VoIP context. These innovations include support for strong encryption making the conversation in a Wi-Fi context quite private (IEEE 802.11i), support for Quality of Service for real-time services such as mobile VoIP (see IEEE 802.11e) and in some cases support for wireless access point to access point call handoff.
VoIP server vendors, upon which VoIP service providers create the service have announced support for integrating mobile handsets into VoIP infrastructures, either natively using SS7 interfaces into the mobile network, or via software based clients running on the mobile handset. BroadSoft is one such vendor of a platform (BroadWorks) that enables mobile integration using either strategy. Enterprise IP PBX vendors have developed, tested and announced capabilities for mobile VoIP users interacting with their business IP-based phone systems.
One implementation of Fixed mobile convergence enables seamless roaming between WIFI and GSM or CDMA networks. Standards and alliances have been developed and technologies have been demonstrated as early as December 2005. Cisco and FirstHand Technologies demonstrated a Wi-Fi to GSM handoff in San Jose, December 5, 2005.
WiFiMobile, founded in 2002 were one of the first mobile VoIP providers with their own self developed VoIP client compatible with all Nokia E and Nseries smartphones.
Recently T-Mobile blocked the access to pure mobile VoIP numbers, which were issued by Truphone for the first time. The issue was widely discussed in the press and although Truphone won an injunction[1], the case is still in the courts while T-Mobile pay only a nominal termination fee.
References
See also
- Voice over IP
- Vowlan — VoIP over a Wi-Fi network
- Fixed mobile convergence
- MoIP